The Ja­panese prime min­is­ter was also the first for­eign leader in­vited to Mar-a-Lago, Trump’s re­sort in Palm Beach. And the re­la­tion­ship blos­somed fur­ther when the pres­i­dent made Japan the first stop in his Asia trip last fall — a visit fea­tur­ing golf, burg­ers and match­ing base­ball caps em­bla­zoned with “Don­ald & Shinzo: Make Alliance Even Greater.”

But de­spite those promis­ing be­gin­nings, Abe’s view of Trump has sud­denly veered to alarm.

Tokyo was dis­mayed last month when Trump sud­denly an­nounced he would meet with Kim Jong Un, the North Korean despot. There had been nary a word of warn­ing, much less con­sul­ta­tion, for Amer­ica’s clos­est friend in the west­ern Pa­cific.

Adding in­sult to in­jury, later the same month, Japan was the only ma­jor Amer­i­can ally not promised an ex­emp­tion from Trump’s hefty new tar­iffs im­posed on steel and alu­minum.

“I think the Ja­panese thought that Abe kind of knew how to han­dle Trump. That was his big mis­take,” said Clyde Prestowitz, a top trade ne­go­tia­tor in the Rea­gan ad­min­is­tra­tion and ex­pert on East Asian eco­nom­ics.

Now, chas­tened and anx­ious, Abe will re­turn to Mar-a-Lago to­day for a cru­cial sum­mit with Trump.

The fo­cus will be on North Korea and its nu­clear weapons pro­gram — an is­sue vastly more ur­gent for Tokyo than for Wash­ing­ton. Al­though Kim may have nu­clear mis­siles ca­pa­ble of hit­ting the West Coast of the United States, North Korea has al­ready demon­strated many times over than it can rain bal­lis­tic hor­ror on Japan any time it chooses.

Whether or not the re­turn to Mar-a-Lago in­cludes a round of golf, the at­mos­phere will be far more tense for Abe than it was on his first visit.

It isn’t just that both men are weighed down by po­lit­i­cal trou­bles at home — Abe from a land-sale scan­dal and Trump by a per­sis­tent in­ves­ti­ga­tion in­volv­ing Rus­sia and his sex­ual in­dul­gences.

But on the larger global stage, the two lead­ers are con­fronting pos­si­bly un­prece­dented events that could cre­ate seis­mic shifts in the Pa­cific re­gion.

Al­though most an­a­lysts say the U.S.-Japan alliance es­tab­lished af­ter World War II re­mains fun­da­men­tally sound, Trump’s uni­lat­eral, spon­ta­neous and un­pre­dictable pro­nounce­ments and ap­proaches to pol­i­cy­mak­ing have raised deepseated con­cerns about the fu­ture of East Asia.

And for the Ja­panese peo­ple, the pos­si­bil­ity that they could no longer rely on the pro­tec­tive um­brella of U.S. mil­i­tary power may be the most un­set­tling de­vel­op­ment in their post­war his­tory.

Since Kim as­sumed power in 2012, Py­ongyang has con­ducted 99 mis­sile tests, in­clud­ing 11 suc­cess­ful launches last year, five of which fell within 200 nau­ti­cal miles of the Ja­panese is­lands, ac­cord­ing to Sheila Smith, a se­nior fel­low for Japan stud­ies at the Coun­cil on For­eign Re­la­tions. One of those tests came when Abe and Trump were din­ing at their first Mar-a-Lago sum­mit.

Kim has claimed his bal­lis­tic mis­siles could even­tu­ally reach the United States.

Trump’s at­ti­tude to­ward Kim, how­ever, has vac­il­lated from sug­gest­ing he would wel­come the North Korean ruler for “a ham­burger on a con­fer­ence ta­ble” to ridi­cul­ing him as “lit­tle rocket man,” and threat­en­ing to meet Kim’s bel­li­cose talk against the United States “with fire and fury.”

This month, Trump said his ad­min­is­tra­tion has been in touch with North Korean of­fi­cials. “We’ll be meet­ing with them some­time in May or early June, and I think there will be great re­spect paid by both par­ties,” he told re­porters at a Cab­i­net meet­ing.

What wor­ries Abe, as well as the Ja­panese peo­ple and the larger for­eign re­la­tions com­mu­nity, is that Trump, in his de­sire to bro­ker a deal break­ing through a long stale­mate, will set­tle for some­thing that could leave the re­gion vul­ner­a­ble, and no one more so than Japan.

Kim could pro­pose a deal in which the United States cur­tails re­gional mil­i­tary ex­er­cises in ex­change for a North Korean freeze on its test­ing of bal­lis­tic mis­siles and nu­clear weapons.

The freeze-for-freeze idea has been floated by China and Rus­sia be­fore, but is highly un­pop­u­lar in Japan as well as with con­ser­va­tives in South Korea, said Michael J. Green, se­nior vice pres­i­dent and Japan chair at the Cen­ter for Strate­gic and In­ter­na­tional Stud­ies.

Crit­ics of the idea say it would be an empty prom­ise en­abling Py­ongyang to con­tinue de­vel­op­ing its nu­clear ca­pa­bil­i­ties in secret while the United States stood down mil­i­tar­ily.

“When North Korea says de­nu­cle­ariza­tion of the Korean penin­sula, they mean the U.S. goes first,” Green said. “You guar­an­tee the sur­vival of our regime, which means you pull back your troops, your sanc­tions.

“It’s ba­si­cally mean­ing­less. The North Kore­ans have used this phrase re­peat­edly over the past two decades.”

An­a­lysts ex­pect Abe will have at least two ma­jor asks of Trump on North Korea: The first is that the pres­i­dent raise the is­sue of Py­ongyang’s ab­duc­tion of Ja­panese cit­i­zens, a par­tic­u­larly sen­si­tive mat­ter in Japan. Tokyo has made lit­tle progress ne­go­ti­at­ing for the re­turn of more than a dozen cit­i­zens who were kid­napped by North Korean agents dur­ing the 1970s and 1980s.

The sec­ond could be harder to at­tain: a state­ment from Trump that there will be no re­lax­ation of pres­sure on North Korea, or any change in the Amer­i­can-led mil­i­tary readi­ness or ex­er­cises, un­til Py­ongyang takes con­crete, ver­i­fi­able steps to de­nu­cle­arize.

But even a com­mit­ment from Trump that he will de­mand a to­tal dis­man­tling of North Korea’s nu­clear pro­gram may not be enough to re­as­sure the Ja­panese.

“Trump has been volatile on many is­sues; that’s what many peo­ple worry about,” said Takeo Hoshi, di­rec­tor of the Japan pro­gram at Stan­ford’s Shoren­stein Asia-Pa­cific Re­search Cen­ter. “If he meets di­rectly with Kim Jong Un, he might say some­thing he shouldn’t, or some­thing spon­ta­neously.” Then there’s the mat­ter of trade. Al­though the pres­i­dent has re­served his harsh­est words and ac­tions for China, in­clud­ing threats to im­pose tar­iffs on as much as $150 bil­lion of Chi­nese goods, Trump many years ear­lier had voiced sim­i­lar dis­dain for Japan’s trade and eco­nomic poli­cies, some­thing that sur­faced dur­ing the 2016 pres­i­den­tial cam­paign.

Many ex­perts think Trump snubbed Japan on metal tar­iff ex­emp­tions to ex­ert lever­age on Tokyo to cut a trade deal. “The U.S. wants Japan to com­plain about the tar­iff and then wants to talk about a bi­lat­eral treaty,” said Ha­jime Izumi, pro­fes­sor of in­ter­na­tional re­la­tions at Tokyo In­ter­na­tional Univer­sity.

Abe will be re­luc­tant to com­mit to launch­ing two-way trade ne­go­ti­a­tions, know­ing that Trump of­fi­cials will in­sist on sub­stan­tial mar­ket open­ings, es­pe­cially in agri­cul­ture, said Mireya So­lis, a Japan scholar at the Brook­ings In­sti­tu­tion. As much as Abe would like to get an ex­emp­tion on metal tar­iffs, the po­lit­i­cal cost of cav­ing in to Trump’s pres­sure for a trade deal may be far greater for the prime min­is­ter.

Their sum­mit dis­cus­sions on trade will be fur­ther com­pli­cated by Trump’s im­promptu re­marks on Thurs­day that he is con­sid­er­ing re­join­ing the Trans-Pa­cific Part­ner­ship, a sweep­ing trade pact that the Obama ad­min­is­tra­tion ne­go­ti­ated with Japan and 10 other na­tions.

Trump trashed the deal dur­ing the cam­paign as bad for Amer­ica, and the pres­i­dent pulled the United States out of it shortly af­ter he took of­fice. But now he is weigh­ing whether the TPP, as it’s known, might be use­ful af­ter all.